1. Field of the Invention
The present invention relates to an ink for ink jet recording comprising an aqueous colored fine particle dispersion containing an oil-soluble dye, a method of manufacturing the ink for ink jet recording, and an ink jet recording method using the ink for ink jet recording. In particular, the present invention relates to an ink for ink jet recording preferable for a thermal, piezoelectric, electric field or acoustic ink jet recording system, excellent in the qualities of recorded images, superior in image water resistance and image fastness properties and excellent in the stability of the ink with time and in discharge stability, as well as a method of manufacturing said ink for ink jet recording and an ink jet recording method using the same.
2. Description of the Related Art
As computers have spread in recent years, ink jet printers are widely utilized for printing on paper, film, cloth, etc. not only in offices but also in homes. As inks for ink jet recording, there are known oily, aqueous and solid inks, among which the aqueous inks are mainly used, because of advantages such as easy production, handling, smelling, safety, etc.
Many of these aqueous inks make use of water-soluble dyes to be dissolved in a molecular state, so there are the advantages of high transparency and high color density, but because these dyes are water-soluble, there are the problem of insufficient water resistance causing bleeding which deteriorates qualities upon printing on paper, as well as poor light resistance.
For the purpose of solving the problems described above, aqueous inks using pigments or dispersed dyes are proposed in e.g. JP-A 56-157468, JP-A 4-18468, JP-A 8-183920, JP-A 10-110126 and JP-A 10-195355.
However, there are the problems that the water resistance of these aqueous inks is improved at a certain degree but is still not satisfactory, the pigment inks are inferior in coloration to the dye inks, the above pigment inks or dye-dispersed inks are poor in shell stability and easily cause clogging in nozzles for discharge of ink.
In addition, a recording paper provided thereon with an ink receiving layer containing a porous inorganic pigment (hereinafter also referred to as xe2x80x9cphotograph-quality paperxe2x80x9d), which came to be used with an increasing demand for high-quality pictures in recent ink jet technology, is poor in stainability with said aqueous inks using pigments or dispersed dyes, and such pigments or dyes are easily removed from the surface upon rubbing with hands.
In addition, JP-A 58-45272, JP-A 6-340835, JP-A 7-268254, JP-A 7-268257 and JP-A 7-268260 propose respectively a method wherein a dye is included in polyurethane- or polyester-dispersed particles.
However, the dispersions described in these literatures have the disadvantage that colored particles excellent in dispersion stability are hardly obtained when the dye is included at a desired concentration, and these dispersions also have the above-described problem of removal of the dye.
Further, JP-A 10-279873 discloses a method of producing colored polymer fine particles by dissolving an acrylic polymer and an oil-soluble dye in an organic solvent, dispersing them, and removing the organic solvent, but there is a problem with the qualities of recorded images particularly on a photograph-quality paper medium or with stability in continuous recording, and another problem is that the stability of the dispersion with time cannot be satisfactory.
On the other hand, JP-B 5-76977 discloses an ink composition wherein an oil-soluble dye is dissolved and dispersed in an organic solvent having low water solubility and specific gravity similar to that of water, but it was revealed that the organic solvent defined therein is generally poor in compatibility with the oil-soluble dye, thus making recording density low, and in some cases the dye is precipitated during storage to cause clogging of nozzles. Further, this dispersion similar to those dispersions described above also has a problem in stability with time.
The problem of the present invention is to solve the problems described in the prior art described above thereby achieving the following object.
The object of the present invention is to provide an ink for ink jet recording preferable for a thermal, piezoelectric, electric field or acoustic ink jet recording system, not depending on paper, excellent in color reproduction and color tone upon printing on an arbitrarily selected paper, capable of high recording density, excellent in ink penetration into a photograph-quality paper, solving the problem of staining just after printing, excellent in image water resistance and image fastness properties, and also excellent in the stability of the ink with time and in discharge stability, a method of manufacturing said ink for ink jet recording, and an ink jet recording method capable of high-quality recording by use of said ink for ink jet recording.
The means for solving the problem described above is as follows. That is, the present invention relates to an ink for ink jet recording which includes a water-insoluble ionic group-containing polymer added to a colored fine particle dispersion containing at least a hydrophobic high-boiling organic solvent having a boiling point of 150xc2x0 C. or more and an oil-soluble dye.
The ink for ink jet recording may be characterized in that the water-insoluble ionic group-containing polymer is converted by emulsification dispersion into a fine particle dispersion and added to the colored fine particle dispersion.
The ink for ink jet recording may be characterized in that the oil-soluble dye is represented by formula (I): 
wherein X represents a residue of a color-photographic coupler; A represents xe2x80x94NR4R5 or a hydroxyl group; R4 and R5 each independently represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group; B1 represents xe2x95x90C(R6)xe2x80x94 or xe2x95x90Nxe2x80x94; B2 represents xe2x80x94C(R7)xe2x95x90 or xe2x80x94Nxe2x95x90; R2, R3, R6 and R7 each independently represents a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, xe2x80x94OR51, xe2x80x94SR52, xe2x80x94CO2R53, xe2x80x94OCOR54, xe2x80x94NR55R56, xe2x80x94CONR57R58, xe2x80x94SO2R59, xe2x80x94SO2NR60R61, xe2x80x94NR62CONR63R64, xe2x80x94NR65CO2R66, xe2x80x94COR67, xe2x80x94NR68COR69 or xe2x80x94NR70SO2R71; R51, R52, R53, R54, R55, R56, R57, R58, R59, R60, R61, R62, R63, R64, R65, R66, R67, R68, R69, R70 and R71 each independently represents a hydrogen atom, an aliphatic group or an aromatic group; and R2 and R3, R3 and R4, R4 and R5, R5 and R6, and R6 and R7 may be bound to each other form a ring.
The ink for ink jet recording may be characterized in that the content of the hydrophobic high-boiling organic solvent in the colored fine particles is 25% by weight or more.
The ink for ink jet recording may be characterized in that the water-insoluble ionic group-containing polymer has 0.1 to 3.0 mmol/g of ionic groups.
The ink for ink jet recording may be characterized in that the ionic group in the water-insoluble ionic group-containing polymer is a carboxyl group and/or a sulfonic acid group.
The ink for ink jet recording may be characterized in that the relative dielectric constant of the hydrophobic high-boiling organic solvent is 3 to 12 at 25xc2x0 C.
The ink for ink jet recording may be characterized in that the average particle diameter of the colored fine particles in the colored fine particle dispersion is 100 nm or less.
Further, the present invention provides an ink jet recording method which comprises using an ink for ink jet recording described as follows.
The ink jet recording method may be characterized in that an image-receiving material to be recorded comprises an ink receiving layer containing a porous inorganic pigment on a support.
Further, the present invention provides a method of manufacturing an ink for ink jet recording, which includes the steps of allowing colored fine particles containing at least a hydrophobic high-boiling organic solvent having a boiling point of 150xc2x0 C. or more and an oil-soluble dye to be dispersed in an aqueous medium to prepare a colored fine particle dispersion, and mixing a fine particle dispersion prepared by emulsification dispersion of a water-insoluble ionic group-containing polymer with the colored fine particle dispersion.